In the fast-food industry, it is necessary to have a supply of cooked products available at all times to meet the needs of the customers. The food products are normally prepared in large quantities and placed in holding cabinets to maintain them in a heated condition until they are needed.
There are basically two types of holding cabinets, namely, those which control only the temperature of the products, and those which control both temperature and moisture content. If the products being held are of the type which have a tendency to lose moisture and dry out, it is necessary to control the moisture content of the heated air being circulated within the cabinet. There are, however, a number of food products which do not require an environment in which moisture is added to the air being circulated. In fact, excessive moisture may be deleterious to the quality of the product. For example, products which are cooked in a batter, or bakery products, such as rolls and buns, will become soggy if exposed to excessive moisture. Consequently, there are numerous applications wherein it is unnecessary to add moisture to the circulating air, and under such conditions there is no need to employ holding cabinets equipped with expensive moisture control units.
A principal difficulty with presently known holding cabinets, irrespective of their type, is their inability to maintain a stabilized uniform temperature within the cabinet. The problem of temperature stabilization is magnified by the fact that the cabinet must be repeatedly opened and closed to permit the products to be removed. Another disadvantage is the fact that most holding cabinets are closed systems in that they simply circulate the air contained within the cabinet, the cabinet being exposed to outside fresh air only when the cabinet is opened. This leads to over-drying of the air within the cabinet which can be a problem even in instances where humidity control is not normally required. In addition, it is often difficult to maintain a stabilized temperature within the cabinet even if the temperature is thermostatically controlled due to the fact that the heating elements will continue to heat the air for a substantial length of time after they have been turned off, with the result that the temperature will fluctuate over relatively wide limits. Difficulties are also experienced in achieving uniform air distribution throughout the holding cabinet, particularly in areas which are remote from the air return.
The present invention overcomes the difficulties encountered with known holding cabinets by providing a cabinet construction which is particularly suited for products which do not require an humidified environment. The basic construction of the holding cabinet of the present invention is similar to that disclosed in U.S. Pat. No. 4,237,623, issued Dec. 9, 1980, directed to a humidified holding cabinet. However, a number of significant modifications and changes have been made in order to provide a cabinet which does not require a humidifying system and yet will maintain a stabilized temperature throughout.